Apparatus for determining the listening habits of wave signal receivers users



HABITS OF WAVE SIGNAL RECEIVER USERS 3 Sheets-Sheet 1 Filed Feb. 11,1948 8? 22.522 528% .1 v o o q. ow i L- E. Z 1 r: g 528% 56 v5 u H A \7A8 352 52% 4 a o o. 3 i i, u i N 628% 56 8. e5 2&3 3.5m 1 Ni as: N J .m55 0 mm 8 2.3 q IN. lllllllll ||||ll|l|\| MN OZ m F SN .5585 J v?INVENTOR. Henry A. Rohmel '97. 1 i/yw Oct. 11, 1949. H A. *RAHMEL2,434,734

APPARATUS FOR DETERMINING THE LISTENING HABITS OF WAVE SIGNAL RECEIVERUSERS 3 Sheets-Sheet 2 Filed Feb. 11, 194B mmzwuum OwZDF OwxE awmmuzwuwm OuZDh aux-u INVENTOR. Henry A. Rohmel Gen 11, 1949. H. A.RAHM-EL 2,484,734

APPARATUS FOR DETERMINING THE LISTENING mmms 0F WAVE SIGNAL RECEIVERusans Eiled Feb. 11, 1948 3' Sheets-Sheet 3 FIG. 2

IN V EIv TOR.

Henry ARM; 1 Wn/ $362? Patented Oct. 11, 1949 APPARATUS FOR DETERMININGm LIS- TEN'ING HABITS OF WAVE SIGNAL BE- CEIVER USERS Henry A. Rahmel,Evanston, IIL, aaslgnor to A. C- Nlelscn Company, Chicago, 111., acorporation of Illinois Application February 11, 1948, Sula] No. 7,648

6 Claims.

The present invention relates to app determining the listening habits ofwave signal receiver users. More particularly the present invention isconcerned with apparatus for making a record with respect to time of thetuning condition of wave signal receivers located in predetermined homeswhich includes making such a record for all the receivers disposed inthe particular homes under consideration even though such homes aremulti-receiver homes and also if desired producing records at a centralpoint with respect to the receivers in a plurality of homes.

In recent years numerous arrangements have been suggested for recordingthe listening habits of wave signal receiver users, whereby withinstrumented methods a continuous record of the transmitting stations towhich a wave signal receiver is tuned may be made, and from which it isreadily possible to analyze the listening habits of such users andprepare reliable information with respect to such listening habits.

It will be understood that in such instrumented methods for determiningthe listening habits of wave signal receiver users, the receivers in alarge number of homes are metered or monitored to aiford the basicinformation from which the analysis can be made. From this basicinformation a stat stical analysis of the various factors affecting thesales eflectiveness of particular radio programs may be arrived at. Insuch a system employing apparatus for recording the listening habits oiwave signal receiver users it is contemplated that the selection of thesystem collaborator homes. that is. the homes in which radio receiveruse is to be loggedshall be on a basis such that all of the variousfactors aflecting any process of sampling public opinion, such, forexample, as the number of potential listeners. religion. economicaiiluence, etc, are accounted for on a weighted basis.

Instrumented methods for determining the listening habits of home radioreceiver users generally involve the use of a recording device operatingin conjunction with each collaborator receiver used in the samplingsystem to record the extent of use of the receiver and to record as afunction of time the wave signal transmitter to which the receiver istuned for program reception. The usual device of this character embodiesfacilities for driving a movable recording or record receiving elementsuch as a movable paper tape, magnetic tape or wire or other recordingtape or medium in a predetermined manner together with translating meansfor variably positioning suitable recording means such as a stylus orthe like relative to the recording element in accordance with changes orthe tuning of the wave signal receiver. If the recording element movesat a constant speed or in some determinable relationship with respect totime, the record on the recording element not only provides informationas to the particular transmitting statlcn or"'statlons to which thereceiver is tuned, but also gives accurate information with reference tohe time; such receiver is tuned to such various transmitting stations.

In general two diiierent types of instrument have been used to produce arecord of the extent of receiver use and themarticular transmitters towhich the receiver is tuned for program reception during, abredetermined calendar period. The first or all mechanical type ofdevice emplays a mechanical connection between the control means foroperating the resonant frequency varying device (which control meansmight be the tuning shaft of the ganged condensers of a receiver), andthe recording stylus of the recorder. The recording stylus is movedtransversely of the recording element in accordance with the angularsetting imparted to the condenser tuning' shaft whereby a record oi theparticular tuning condition of the receiver is obtained. If the tape isdriven at a constant speed then a record of the tuning condition withrespect to time is obtained. The connection between the rccording meanssuch as the stylus and the receiver tuning shalt dictates thepositioning of the recorder in the receiver cabinet which bars its usein connection with small receivers having limited unoccupied cabinetspace.

The second type of such instrument used heretofore might be termed anelectro-mechanical device, in that an electro-mechanical translatingsystem is interposed. between the high frequency signal channel of thereceiver and the station recording stylus. to control the movement ofthe stylus in its operation to record on a time basis the particulartransmitters from which programs are received. Generally such a devicerequires a connection with the local oscillator of receivers of thesuperheterodyne type and is not adaptable for use with receivers otherthan the superheterodyne type. Furthermore this type of device generallyrequires accurate frequency measuring apparatus to be located at thereceiver. Such apparatus generally is bulky in the first place and inthe second place is usually quite delicate and consequently should notbe subjected to lure or the like which it might receive throughmovement. for example, of the wave signal receiver when re-arranging theiumiture in a particular room where the receiver is located.

It would be desirable to provide apparatus for producing a record of theextent of receiver use which is applicable to any type of receiverwhether of the superheterodyne type or not. It would furthermore bedesirable that any apparatus which must be installed at the receiver besimple and compact so as to be applicable to substantially all receiversregardless of size. The recording and translating equipment forproducing a record of the tuning condition of the receiver should becapable of being located remotely from the receiver such for example asin the basement or a closet of a home without the requirement of specialelectrical or mechanical connections between the receiver and suchrecording apparatus. In many cases it may be desirable to have therecording equipment located at a central office to record informationfrom a plurality of homes which can be accomplished by employingsuitable links such as telephone wires or space links employing beamedultra high frequency radio waves. It is furthermore desirable that a,single recording and translating unit should be capable of recording thetuning conditions of all the wave signal receivers in a single home (inthe event that the recorder is located at a central ofllce a singlerecording device may be used to record the tuning condition of thereceivers in a plurality of homes) while still giving completeinformation with respect to each receiver.

It will be understood that in any particular locality the number oftransmitting stations to which a wave signal receiver is generally tunedis fairly limited. One factor which limits the number of transmittingstations to which a receiver is tuned is of course the relative range ofthe receiver. Another factor is the relative range of the transmittingstation. In addition the advantageous reception obtainable from a finitenumber of stations over the reception of other stations which might betuned in but whose transmitting characteristics are not too favorablefor good program reception mitigates against tuning the receiver to morethan a limited number of transmitters. Furthermore. with the presentnetworks whereby the identical programs are carried by numerous stationsit is rare indeed when a receiver is tuned to other than a limitednumber of transmitting stations. It would be desirable therefore toprovide a s m lifled arrangement which will provide for recording in amanner which can readily be decoded the tuning condition of a wavesignal receiver to a plurality of predetermined stations which wouldinclude all those stations to which the receiver is likely tobe tunedtogether with additional information which would indicate the time thata receiver is tuned to stations other than the finite number of stationsto which the receiver is normally tuned. It will be understood that ifthe wave signal receiver is tuned to stations other than the finitenumber for a substantial period of time that some of such other stationsshould be included within the finite number.

In apparatus commonly employed heretofore the transverse position of atrace or record on a recording element such as a tape was indicative ofthe tuning condition of the receiver. It will be understood that due tothe apparent variable band width of transmitting frequencies received atthe wave signal receiver that certain stations can be tuned in over aconsiderable area of the tuning scale whereas others are confined to avery narrow area. This has complicated matters from the standpoint ofdecoding such records or tapes and it would be desirable to provide anarrangement in which the traces on the tape appear in narrowly confinedchannels equally spaced from one another thereby greatly to facilitatethe decoding operation.

Accordingly it is an object of the present invention to provide a newand improved apparatus for recording the listening habits of wave signalreceiver users.

It is a further object of the present invention to at least in partobviate the above mentioned disadvantages of prior art systems andapparatus for recording the tuning condition of one or more wave signalreceivers.

It is another object of the present invention to provide improvedapparatus of the character described for recording information withrespect to the tuning conditions of a plurality of wave signal receiverswith a relatively small amount of apparatus the bulk of which is locatedat a point remote from the receivers while the apparatus located at thereceivers is of such small size as to be capable of being disposedwithin the available cabinet space of substantially all types ofreceivers.

It is another object of the present invention to provide a new andimproved apparatus of the character referred to above having all of theadvantages enumerated above.

Still another object of the present invention is to provide an apparatusemploying a single record receiving element for recording informationwith respect to the tuning condition of a plurality of remotely locatedwave signal receivers with the information recorded in the form oftraces disposed in uniformly spaced channels so as to be readilydecoded.

A still further object of the present invention is to provide new andimproved apparatus wherein a proper record of the tuning condition ofone or more wave signal receivers is made regardless of how thereceivers are tuned to the various channels of interest.

Further objects and advantages of the present invention will becomeapparent as the following description proceeds and the features ofnovelty which characterize the invention willbe pointed out withparticularity in the claims annexed to and forming a part of thisspecification.

For a better understanding of the present invention reference may be hadto the accompanying drawings in which:

Figs. 1a and lb are diagrammatic illustrations showing first and secondportions of a system and apparatus employing the present inventionarranged so as to be united into a single disclosure;

Fig. 2 is an enlarged view setting forth certain details of a portion ofFig. 1a of the drawings; and

Fig. 3 is a sectional view taken on line 3-3 of Fig. 2.

It will be understood that the present invention is equally applicableto homes employing only a single wave signal receiver or to homes havinga plurality of receivers. It will furthermore be understood that thesample of homes from which the statistical analysis is to be obtained isdetermined without knowledge of the number of receivers disposedtherein. Consequently it is essential for the apparatus to be equallycapable of monitoring all of the receivers within a particular homewhether it be one or more, or in many cases be capable of monitoring thereceivers in a plurality of homes by recording the tuning conditions ata central ofilce or the like. By way of example there is illustrated inFigs. 1a and 1b of the drawings three wave signal receivers designatedgenerally by the reierence numeral III characterized by a suitablesubscript to distinguish between the receivers. As illustrated in Fig.there are provided wave signal receivers Illa, "lb, and Illcrespectively. All of these receivers are indicated diagrammaticallyalthough the receiver Illa is shown in slightly more detail. It will beunderstood that these wave signal receivers may be identical but morethan likely they will be quite different with one of the receiversprobably being a console model while the others might be small tablemodels or even a portable radio. Each of the receivers is indicated ascomprising an antenna ground circuit II and signal reproducer or loudspeaker i2. As was mentioned above although these receivers are likelyto be of the superheterodyne type it is not essential as far as thepresent invention is concerned that they be of this type. By way ofexample it is assumed that all of these receivers are located in asingle home and connected to the house wiring circuit 25 which isillustrated with dashed line portions to indicate that the receiversIlla, Inb and We are located remotely from each other. However, thepresent invention is equally applicable to arrangements where thereceivers are located in different homes and the recorder at a centraloflice, the only different consideration being the links, space orotherwise, interconnecting the portions of the system since in thelatter case no common house wiring circuit is available. However, aspace link or telephone lines could be employed in such a situation.

Referring now to wave signal receiver Illa which is representative ofthe receivers Illb and Ilc it is illustrated as including a power supplyunit generally indicated at it! which is connected by means of a plugconnector I4 with a suitable source of power. The power supply unit I3in cludes the conventional cn-off switch which preferably is combinedwith the manual volume control means in the conventional manner. Asillustrated the control knob i5 controls the on-ofl switch comprisingthe contacts l6 and H which are connected in series with a suitablewinding I8, which may comprise a primary winding of a suitabletransformer. The receiver Illa is also illustrated as comprising aconventional tuning knob is which is mounted on a suitable tuning shaftfor controlling the position of the'resonant frequency varying meanssuch as the ganged condensers if condenser tuning is employed or theposition of the iron cores if permeability tuning is employed. It willbe understood that the tuning shaft might be positioned by push buttonsor push buttons might be employed to control the tuning condition of thewave signal receiver without in any way affecting the position of arotatable tuning shaft. As will become apparent from the followingdescription the present invention is readily applicable to push buttonoperated receivers whether they control the position oi the tuning shaftor not.

If the wave signal receiver employs a tuning shaft which is positionedat various positions whenever the receiver is tuned to transmittingstations whose signal is receivable by said receiver, it will beapparent that the position of the tuning shaft will be indicative of thetuning condition of the receiver. Experience has shown that with a veryhigh percentage of receivers a mechanical link can be connected to thedial drum. For the purpose or simplifying the cus closure, the presentinvention has hem specifically illustrated in that connection.

since,ashasbeenpointedoutnbove.therecording and translating eq ipmentwhich is fairly sensitive and somewhat bulky apparatus is located at apoint remote from the receivers such as Illa it is necessary to provideat each receiver apparatus which is capable oi. to a remote pointinformation pertinent to the tuning condition of the associatedreceives. In accordance with the present invention this apparatus isvery small and compact so that it may be disposed in the availablecabinet space of most receivers. As illustrated each wave algnalreceiver such as Ila, Nb, and Illc has emaciated therewith an apparatusprovided in decadence with the present invention which may be referredto as a receiver attachment. These receiver attachments are designatedby the reiermce numerals 20a, 10b and 20c for the receivers Ila, Ilb andlie. respectively. The receiver t 21a is shown in detail in Fig. 1a ofthe drawings and essentially comprises three units as follows: a powersupply unit 22, an audio olclllatm' II, and an oscillator 24 which maybe a radio :lrcquency oscillator when the receivers are all located in asingle home, but which might also comprise an ultra high frequencyoscillator where the receivers in different homes are monitored and arecord produced at a central ofllce. The power supply unit 22 ispreferably connected to a source of alternating current such as thehouse wiring circuit generally designated by the reference numeral 25through a suitable plug connector I. In order that the receiverattachment Illais energized only when the receiver lid is turned on (andsimilarly for the receiver attachments lib and 20c) there is provided inthe power supply unit 22 a relay 21 having its winding 28 connected inseries with the combined volume control and oil-0i! switch I5, I6 and I!of the wave signal receiver Illa. Consequently whenever the wave signalreceiver Illa is turned on the flow of current to the receiver throughthe plug connectors 26 and It causes relay 2! to be energized to closeits normally open contacts 21a. It will be apparent that with thearrangement descrflied the receiver attachment 20a may be applied to thereceiver Ifla as far as the electrical circuit thereof is concernedmerely by removing one portion of the plug connector I4 from theconventional power circuit and instead applying the correspondingportion oithe plug connector 2' ot the power supply unit 22 to the powercircuit and connecting the plug connector l4 as shown in Fla. la of thedrawing.

The contacts 210. of the relay II are illustrated as controlling theenergization of the primary winding 3|) of a transformer Ii includingsecondary windings 32 and 33 respectively. The secondary winding 32preferably supplies the filament voltage for the electron dischargevalves employed in the receiver attachment 28a. The secondary winding 33on the other hand is connected to the anodes of a twin diode 3!connected in the circuit of a full wave rectifier so as to provide atthe terminals 35 and between which there is provided a resistor 31. adirect current potential suitably filtered as by means of a filteringunit 38.

For the purpose of providing a signal uniquely representative of thetuning condition of the wave signal receiver associated therewith suchas the wave signal receiver Ilia there is provided an audio oscillator23 which may be any suitable form of audio oscillator but which has beenspecifically illustrated as an RC oscillator of the Wien bridge type. Asillustrated the audio oscillator 23 is very similar to that disclosed inthe August 1946 issue of Radio News, pages 38 to 40, entitled Audiooscillators," by J. C. Hoadley. The R or Wien bridge oscillator 23operates directly at audio frequencies. As illustrated it comprises atwo-stage audio amplifier including triodes 40 and 4| respectively and aresistancecapacitance bridge generally referred to as an RC bridge,which is at the same time regenerative and degenerative. The RC bridgecomprises the capacitors 42 and 43 which are preferably identical inrating and two sets of resistors generally designated by the referencenumerals 44 and 45, one resistor from each set being adapted to beselectively rendered effective at any one time. The set of resistors 44which are in a sense arranged in parallel, but only one of which iseffective at any one time, are specifically designated as 44a, 44b, 44c,44d, 44e, 44f, 449, Ii, 44: and 447'. Similarly the resistors 45 aredesignated as 45a, 45b, 45c, 45d, 45c, 45;, 459, 45h, 451 and 459'respectively. The resistors marked with the same subscript preferablyhave identical values of resistance but the resistors having differentsubscripts differ from each other and as schematically illustrated haveincreasing values of resistance as the subscripts change from a to 7'.One terminal of each of the resistors 44a to 44 inclusive is connectedto a common terminal and to one terminal of the capacitor 44. Asillustrated this terminal is grounded as indicated at 48 through asuitable capacitor 41. The other ends of the resistors 44a, to 449' arerespectively connected to spaced contact members 48a, 48b, 48c, 48d,48c, 48!, 489, 48h, 481 and 487'. Similarly the resistors 45a to 457'inclusive have a common terminal which is connected to one terminal ofthe capacitor 42. The other terminals of the resistors 45 are connectedto spaced contact members 49a, 49b, 49c, 49d, 49c, 491, 49g, 49h, 49f,and 49;} which are disposed in a linear relationship opposite thecorresponding contact members 48a, 48b, 48c, 48d, 48e, 48f, 489, 4th, 48and 481 so as to be engageable by a suitable sliding switch contact 50,the contacts with similar subscripts being simultaneously engaged. Thesliding contact 50 is furthermore adapted to be connected by a flexibleconductor 5| to the other terminal of the capacitor 43. The otherterminal of the capacitor 42 is connected through a suitable adjustableresistor 53 with the cathode of the triode 40. The resistor 53 ispreferably a feed back resistor which is adjustable so that the feedback maybe adjusted to an optimum value. The flexible terminal 5| isalso connected to the control electrode of the trlode 40.

In order than an audio frequency is producible by the audio oscillator23 when the sliding switch contact 50 is not in engagement with any ofthe associated contacts 44 and 45 there are provided a pair of resistors52a and 52b which are connected in parallel with the particularresistors 44 and 45 rendered efiective by the sliding switch contact 50.These resistors are preferably relatively large to insure an audiofrequency output of 40 cycles, for example, if no other pair ofresistors 44 and 45 are connected into the RC circuit.

For the purpose of improving the stability of the audio oscillator 24there is preferably provided in the cathode circuit of the triode 40 aresistor 54 in the form of a low wattage lamp whose resistance varieswith temperature. When the triode 40 attempts to draw more current thetemperature of the lamp 54 increases. thereby efl'ectively increasingthe bias on the triode 40 and increasing the degenerative effect.Consequently the resistor or lamp 54 tends automatically to hold theoutput of the oscillator constant and the distortion to a low value. Theanode of the triode 4|! is preferably connected to the terminal 46 ofthe power supply unit 22 which eilectively is a source of +3 potentialthrough a voltage dropping resistor 55. This voltage dropping resistoris preferably proportioned so that the average current flowing throughthe lamp or resistor 84 falls on the knee of the lamp's temperatureresistance characteristic whereby the desired stabilizing effect occurs.The plate circuit of the triode 44 is connected by a suitable couplingcondenser 58 to the control electrode of the triode 4|. The anode of thetriode 4| is connected by a coupling capacitor 51 with the RC bridge andspecifically with the terminal of the condenser 42 connected to theadjustable resistor 53. The cathode of the triode 4| is grounded asindicated through a resistor 58. A suitable grid leak for the triode 4|is provided by means of the resistor 59. The coupling capacitor 66should be large it it is desired to maintain oscillation at lowfrequencies. Similarly coupling capacitor 51 must be very large as itworks into a very low resistance composed of the resistors 53 and 54connected in series. Preferably the capacitor 51 is an electrolyticcondenser and works satisfactorily in view of the fact that the directcurrent polarizing voltage is higher thtan the alternating currentvoltage it must handle. The anode of the triode 4| is connected to thesource of +3 potential or in other words to the terminal 38 of the powersupply unit 22 through a suitable voltage dropping resistor 60. Theoutput of the audio frequency oscillator is illustrated as beingobtained from the cathode circuit of the triode BI and is suppliedthrough a coupling capacitor Bl.

It will be understood that the output frequency of the audio oscillator23 may be controlled by varying the capacitance of the capacitors 42 and43 or the resistance of the resistors 44 and 45 or both. When thecapacitors 42 and 43 are equal and the particular resistors 44 and 45which are rendered effective by the movable switch arm ill are equal.and the resistors 52a and 52b are equal, then the frequency of theoutput of the audio oscillator may be given by the following expression:

FRO

where R is the value in ohms of the parallel resistance circuitcomprising the resistor 52a and the particular resistor 44 which isrendered eflective as for example the resistors 44h for the positionindicated in Fig. in of the drawings, and C is the capacitance infarads. If none of the resistors 44 and 45 are rendered efl'ective for aparticular setting it will be apparent that R will comprise theresistance of the resistor 52d. For the purposes of the presentinvention the resistors 441 and 441 preferably have a value such thatthe output frequency of the audio oscillator is approximately 1000cycles and the resistance of the other resistors are decreased in valueso that the frequency steps at the output of the audio oscillator asdliier from each other by about one and one half kilocycles with thehighest frequency beingproducedwhentheresistorstlcandllo are renderedeffective. Whenonly the resistors lid and lib are effective a lowfrequency of the order of 40 cycles or the like appears at the output ofthe audio oscillator which is indicative of tuning the wave signalreceiver "a to a station for which no channel is provided in thereceiver attachment lilo or in. other words to what may be termed tuningto all other stations."

For the purpose of controlling the output frequency of the audiooscillator 23 in dependence upon the tuning condition of the associatedwave signal receiver III the slidable contact switch It which engageswith the contacts ll and It is connected by suitable means, such as aBowden wire or the like generally indicated by the reference numeral 68.with the manual tuningtnob II or the tuning shaft so that if the tuningcondition of the wave signal receiver it is changed the resistances inthe RC bridge of the Wien bridge oscillator as are selectively changedand consequently the output frequencies of the audio oscillator arevaried. Although the contacts it and the contacts I! are schematicallyillustrated in fixed positions in Fig. in of the drawings, it will beunderstood that these contacts are adlustably spaced so that any desiredchannels may be chosen within the limit of the number provided for bythe contacts 48 and It. It will be understood that any suitable meansfor providing adjustable positioning of the contacts 48 and 49 may beemployed. One arrangement foraccomplishingthisisdisclosedinFlgsJandliofthedrawlngs where thecorresponding parts are designated by the same reference numerals as inthe preceding figures. As illustrated the switch comprising the slidablecontact Ill and the relatively stationary contacts it and 40 includes aninsulating base Ill having defined therein a plurality of elongatedrecesses Ill and ill. The longitudinally extending edges of the recessesIll and It! are serrated as shown at I83 in Fig. 2 of the drawings.Preferably the base ill is molded from suitable insulating material andthe serrations I along the edges of the recesses Ill and it! are formedduring this molding process. The contacts II and 40 are indicated asbeing provided with cooperating serrations along the ends thereof sothat they may be positioned at any place along the recesses "I and II!respectively. The cooperating serrations prevent movement of thecontacts ll and l! in a direction along the longitudinal axis of theserecesses. To retain the contacts l8 and 49 in any desired position apair of insulating retaining bars or clamping blocks ill and I" areprovided which clampingly hold the contacts in position as is clearlyshown in Figs. 2 and 3 of the drawings. Preferably the clamping blocksIll and III are held to the base I" by suitable screws III. A sufficientportion of each of the contacts 08 and 49 is exposed so as to beengageable by the slidable contact 50. As illustrated the contacts lland "extend very slightly above the top surface of the base I" to insuregood electrical contact with the sliding switch contact 80.

, To further insure proper engagement of the sliding contact II with thecontacts I and 48, the base I" is preferably provided with an elongatedslot IBI for receiving a suitable bolt iBIl extending through thesliding contact It. A suitable resilient means in engaging along thebottom of the base I80 supplies the desired contact pres- 10 sure as isobvious from Fig. 3 of the drawlngi. The slidable contact 50 isconnected with the Bowden wire it referred to above.

It should be understood that in the event that the wave signal receiver"la is provided with push buttons suitable means may be provided toinsure the connection of the proper resistances l4 and 45 in the RCbridge of the audio oscillator It in dependence upon the particular pushbutton which is actuated. Although ten frequency steps are illustratedfor the audio oscillator 23 exclusive of the "all other" stationsfrequency condition, it will be apparent that a larger or smaller numbermay be employed depending upon the number of stations to which the wavesignal receiver It is normally tuned. It will furthermore be understoodthat the various frequency steps of the audio output of the oscillator23 may be representative of channels in the AM, FM. or television bandsor a combination thereof so that the tuning condition of the wave signalreceiver, regardless of the band to which it is tuned, will be indicatedby a. predetermined audio frequency output of the audio oscillator 23.

It will be understood by those skilled in the art that the apparent bandwidth for particular channels in the various frequency bands of theradio frequency spectrum as viewed at the receiver vary considerablyparticularly in the standard broadcast. band. This is due to both theselectivity curve of the receiver and the non-linearity of the resonantfrequency varying means of the receiver. Thus with some receivers havinga poor selectivity curve a particularly strong transmitting stationhaving a band width of 10 kc. may appear on the receiver dial to have aband width of 50 or more kc. It is of course essential that regardlessof the position of the tuning shaft, for example, of the receiver whentuned to such a station having a wide apparent band width, that the sameaudio output at the oscillator 23 be provided for any position of thetuning shaft that the signal from the particular channel tuned in bysaid receiver can be received. In accordance with the present inventionvariable width contacts are provided which are represented schematicallyin Fig. 1a. of the drawings. It will be understood that any suitablearrangement for obtaining variable width contacts may be employed. Asillustrated in Fig. 2 of the drawings the contacts l8 and it areconstructed in variable widths and the proper width is chosen for theparticular contact so as to conform with the apparent band width of thestation as viewed at the receiver which is represented by the particularcontact. Consequently, where the tuning shaft of the receiver may bemoved over quite an angle while the receiver remains tuned to the samestation, wide contacts such as 48b and 45b are chosen for the associatedchannels in the audio oscillator 23. On the other hand, where the tuningshaft of the receiver can be moved over only a very small angle andstill remain tuned to the same station, very narrow contacts such as 48!and 49; are chosen for the associated channels in the audio oscillator23. In other words the switch comprising the spaced linearly arrangedcontacts 48 and Gil and the sliding contact Bll is designed to insurethe proper audio frequency output for all positions of the tuning shaftof the receiver Illa, that the particular channels provided for in thereceiver attachment 20a can be received. It should be understood thatthe switch comprising the sliding contact 50 and the stationary contacts48 and asserts ll mighttakevariousforms. Asuitsbleswiteh forthispposeisdlsclosedandclsimedina copending application of Prod Krahulec,Serial No. 78,926 flied March 1, 1040, and to the same assignee as thepresent application.

With the arrangement described thus far the different tuning conditionsof the wave signal receivers lea, lit and Mo are represented bydifferent predetermined audio frequencies each different audio frequencybeing indicative of a different tuning condition of the associated wavesignal receiver. In order that a record may be producedat a remote pointof the particular output frequency of the audio oscillators associatedwith each receiver so as to identify the receiver as well as the tuningcondition thereof, each receiver attachment is also provided with anoscillater it which is capable of producing a signal uniquelyrepresentative of the particular receiver. This oscillator may be anultra high frequency os-. cillator or where the receivers beingmonitored are in a single home, a radio frequency oscillator capable ofproducing a radio frequency. The oscillator 24 is referred tohereinafter as a radio frequency oscillator but it should be understoodthat this is by way of example only and it might equally well comprisean ultra high frequency oscillator where this is desirable. Asillustrated the radio frequency oscillator is which is preferablyidentical for each receiver attachment comprises an electron coupledoscillator including the pentode it having an anode it, a cathode ll, acontrol electrode to, a screen srid 6s and a suppressor grid It. Theanode it of the pentode ll is connected to a source of +3 potential,which is the terminal as of the power supply' unit 2!, through a radiofrequency choke coil II and a voltage dropping resistor If. This platecircuit of the pentode it is also connected by means of a couplingcapacitor ll with a suitable antenna 14 if the signal from the receiverattachment 20a is transmitted by space link to a suitable recorder unit.It should be understood however that the output of the plate circuit ofthe radio frequency oscillator 24 might be connected by some other linksuch as for example the power circuit II or other suitable means to theremote point where the recorder to be described hereinafter is located.Preferably when the recorder is located in the multi-receiver home thespace link or the power circuit comprising the conductors I! areemployed since these schemes eliminate the requirement of any additionalconductors connected between the receiver attachment and the remoterecording point. Where the recorder is located at a central oi'dce anultra high frequency space link may be employed. or if desired,telephone wires.

For the purpose of producing a radio frequency signal the radiofrequency oscillator 20 comprises a tank circuit 18 including theinductance I1 and a plurality of capacitors Ila, 'llb, 18c and drespectively adapted to be selectively connected in parallel with theinductance II by means of an adjustable switch II. In other words thecapacitors 18 are arranged in parallelwith one common terminal of all ofthe capacitors connected to one terminal of the inductance I1 and theother terminals of the capacitors Ila, llb, Ito, and lid capacitors 18is such that the frequency output of the radio frequency oscillator 24may be adjusted to either two, three, four or five megacycles de- 12pendingupcnwhichofthsccntactflmm, llc orlldisengagedbytheswitcharmll.One termlnalofthetankcircuit 'ltiseonnectedby with the control elec- Ol.The cathode O1 is connected to a suitable tap lid on the inductance IIand a grid leak resistor is is connected across the triods to cathodecircuit of the pentode ll. The screen grid ltisconnsctedtothesourceof 3potential through a suitable voltage droppingresistortl.Aby-passcondenserllto to the screen arid 00. The suppressor grid It isBounded as indicated at ll. Any suitable means for modulating the radiofrequency output of the R1" oscillator II with the audio frequencyoutput of the audio oscillater it may be provided. As illustrated asuitable coupling transformer I1 is interposed between the couplingcapacitor ii and the control electrode ll of the pcntode ii. A suitableradio frequency choke coll it prevents the radio frequency fromaffecting the audio oscillation. The radio frequency by pass condensersand all are provided to around both ends of the choke coll II for radiofrequencies.

From the above description it will be apparent that the oscillator 24produces a carrier signal which is modulated with the audio frequencyoutput of the audio oscillator II. By employing a radio frequency withinthe frequency range of 1.8 to 5 megacycles, operation in a band whichwill cause a minimum of difliculty from the standpoint of the F. C. C.regulations is provided. of the radio frequency osciladjusted withrespect to signal strength, radiation, and the like to conform with F.C. C. regulations. It will be noted that the adjustable switch II forthe receiver attachments 20a, 20b and 20c is set at different positionswhereby it is readily possible to determine from the frequency of thetransmitted radio frequency signal which receiver is responsible. Inother words means are provided for producing a modulated radio frequencythe tuning condition of the receiver but also uniquely representative ofa particular receiver. If an ultra high frequency oscillator is providedthe signal may be beamed in the desired direction and in this frequencyrange no diinculty with the I". C. C. regulations should be encountered.

For the purpose of producing a record of the frequency output of theaudio oscillators 23 asso ciated with each of the receiver attachments20a, 20b, and 200 with respect to time, so as effectively to produce arecord of the tuning condition of the wave signal receivers lilo, lib,and lilo at all times, there is provided a recording unit and associatedequipment generally indicated by the reference numeral I5 and designatedas the central station. The term "central station is employed since therecording equipment for a plurality of receivers such as Ila, lllb, liloand the like is located at a central point preferably remote from thereceivers at a suitable inconspicuous place in the home such for exampleas the basement, a closet. the attic or the like, or even at a centraloillce remote from the home whereby the receivers in a plurality ofhomes may be menin the receiver midget tubes are employed as well asdual tubes wherever this is possible (the tubes 40 and I are preferablymidget triodes combined in a single as the 6-16), the

signal indicative not only of confined in a small space and furthermoremay comprise equipment which is delicate and which should not besubjected to jars and the like due to moving the equipment around.

Essentially the central station comprises a plurality of fixed tunedradio frequency amplifier-detector units preferably referred to as fixedtuned receivers, one for each of the wave signal receivers beingmonitored or metered Since three wave signal receivers Ito, I01) and Wehave been described the central station is provided with three fixedtuned receivers 00a, 00b and 000 respectively which are identical exceptfor the frequency to which these receivers are tuned. It will beunderstood that the fixed tuned receiver 060 will be tuned to receiveonly the frequency of the radio frequency oscillator 24 in the receiverattachment 20a while the fixed tuned receivers 00b and 060 will be tunedrespectively to receive only the radio frequency outputs of theoscillators 24 associated with the receiver attachments 20b and 20cwhich by virtue of the adjustment of the switch arm are set at differentfrequency values. In addition to the fixed tuned receivers 06a, 06b and06c, the central station 05 further includes a step-tuned audiofrequency amplifier and translating unit generally designated by thereference numeral II and a recording unit generally indicated at 08.

Since the fixed tuned receivers 86a. 06b and 060 are all identical onlythe fixed tuned receiver 06a will be described in detail and thecorresponding parts of the other receivers when illustrated will bedesignated by the same reference numerals marked with the same subscriptas that associated with the reference numeral 00 for the particularreceiver. As illustrated the fixed tuned receiver 06a comprises an inputcircuit specifically illustrated as an antenna ground circuit 00a. Itwill be understood that if the antenna 14 of the receiver attachments a,20b and 20c are dispensed with and instead of a space link the output ofthe radio frequency oscillators 24 is impressed directly on the housewiring circuit 25, then the antenna-ground circuits 09a, 90b and 09cwould also be dispensed with and instead the input circuits for thefixed tuned receivers 00a, 06b and 960 would be connected directly tothe house wiring circuit 25. The antenna-ground circuit 90a for thefixed tuned receiver 00a is connected to a tuned circuit I00 which inturn is coupled to a tuned circuit IOI connected to the input of anelectron discharge valve I02 in the form of a triode acting as a radiofrequency amplifier. The plate circuit of the triode I02 is connected toa source of +3 potential indicated as I03 through a tuned circuit I04.The tuned circuit I04 is furthermore coupled to a tuned cireut I05connected in the input circuit of a triode I06 which also functions as aradio frequency amplifier and whose plate circuit is connected to asource of +3 potential also designated by the reference numeral I03through the tuned circuit I01. It will be understood that the tunedcircuits I00, IIll, I04, I05 and I0! are fixed tuned circuits tuned tothe frequency of the radio frequency oscillator 24 in the particularreceiver attachment with which the fixed tuned receiver is associated.For the fixed tuned receiver 960 these tuned circuits are tuned to thefrequency of the RF oscillator 24 of the receiver attachment 20a, whichas was pointed out above might be a frequency of two megacycles. Thetuned circuits in the fixed tuned receivers 06b and 96c 14 wouldpreferably be tuned to a frequency of three and four megacyclesrespectively. or some other suitable values in the 1.8 to 5 megacyclefrequnecy. range.

The fixed tuned receiver 001: further includes an electron dischargevalve I00 in the form of a diode-triode. the diode section functioningas a detector and being coupled to the tuned circuit I01 by means of aninductance H0. The detector section of the electron discharge valve I00will cause the modulation components of the modulated radio frequencyoutput of the oscillator 24 of the receiver attachment 20a to appearacross the resistor III connected in series with the plate to cathodecircuit thereof. The control electrode of the triode section of theelectron discharge valve I00 is connected to one terminal of theresistor III so as to apply a negative bias thereto when modulationcomponents are detected by the diode section of the valve I09. The

plate circuit of the triode section of the valve I09 is connected to thesource of +13 potential again designated by the reference numeral I03through the winding of a suitable control relay designated by thereference numeral II2a. It will be apparent therefore that a currentcontinually fiows through the winding of the relay II2a and the platecircuit of the triode section of the valve I00 as long as no substantialnegative bias due to detection of the modulation components of themodulated carrier signal appears across the resistor III. The relay II2ais therefore normally energized and is so indicated in Fig. lb of thedrawings. Only upon the receipt of a carrier having a frequency whichthe fixed tuned receiver 06a is capable of receiving does a voltageappear across the resistor I I I which causes a sufficient decrease inthe current flowing in the plate circuit of the triode section of thevalve I08 to cause the relay 2a to be denergized to close its two setsof normally open contacts Illa and II4a.

The detected audio voltage appearing at the plate circuit of the triodesection of the electron discharge valve I09 is connected through asuitable coupling capacitor IIBa to the input of an audio frequencyamplifier comprising the electron discharge valve Ilia, whose controlelectrode is connected to one terminal of the coupling capacitor Ilia.The cathode of the electron discharge valve IIBa is grounded through asuitable resistor II'Ia and the anode is connected to a source of +3potential designated by the reference numeral I03 through a suitablevoltae dropping resistor H0.

The fixed tuned receivers 96b and Mia are identical with the fixed tunedreceiver and similarly include relays H2?) and Il2e respectively andaudio frequency amplifiers comprising elecw tron discharge valves IIGband IIIic respectively.

1 the oscillators 24 in the respective receiver attachments is receivedat the central station 95 and consequently the relays H20, H22) and II2cremain energized to maintain open (as illustrated in Fig. lb of thedrawings) their normally open 7 contacts H3 and I I4, designated withappropriate subscripts. Under these conditions no audio frequency signalis applied to the audio frequency amplifiers comprising the valves Ilia,Iltb or Illc. Whenever one or more of the wave signal receivers Illa, Moand c is turned on however, an audio frequency output will be producedby one or more of the audio frequency oscillators 20 which frequencywill either be indicative of one of the ten channels represented by thevariable resistors 44 and 48. or indicative of tuning of the associatedreceiver to what is termed "all other stations." Consequently theturning on of any receiver I011, I022 or We will cause its associatedreceiver attachment to produce a modulated radio frequency signal whichwill render the associated fixed tuned receiver 96 effective todeenergize its associated relay H2 with the result that the associatedcontacts 3 and H4 are closed. Also the demodulated audio frequencysignal will appear in the parallel connected plate circuits of theelectron discharge valves III.

For the purpose of producing a record indicative of the tuning conditionof the wave signal receivers I00, lilb or He or any others which mightbe provided the step-tuned audio frequency amplifier 01 and recorderunit 98 are provided. As illustrated the step-tuned audio frequencyamplifier and translating unit 91 comprises a pair of electron dischargevalves I20 and HI arranged in cascade in the form of a two-stagestep-tuned amplifier. As illustrated each of the electron dischargevalves I20 and I 2I is in the form of a pentode comprising anodes I22,cathodes I23, control electrodes I24, screen grids I25 and suppressorgrids I26. The control electrode I24 of the electron discharge valve I20is connected to the output of the parallel arranged audio frequencyampliilers Ilia, IIlib, and H60 through a suitable coupling capacitor!28 and a potentiometer I29 in the form of a resistor having oneterminalgrounded and the other terminal connected to the coupling capacitor I20.A variable tap on the potentiometer I29 permits appropriate adjustmentof the magnitude of the audio frequency voltage applied to the controlelectrod I24 of the electron discharge valve I20 comprising the firststage of the two-stage step tuned amplifier. The suppressor grid I26 ofeach pentode I20 and I2I is connected to its associated cathode I20which in turn is grounded through a suitable resistor I30. The screengrids I25 of each of the electron discharge valves I20 and I2| areconnected to the source of B potential I03 through their respectivevoltage dropping resistors IOI. B potential from the source I03 issupplied to each plate I22 through suitable respective inductances I02.The plate circuit of the pentode I22 is also coupled to the controlelectrode I24 of the pentode I2I through a suitable coupling capacitorI33. The control electrode I24 is provided with a. suitable grid leakresistor I35.

For the purpose of providing tuned circuits for each of the stages ofthe audio frequency amplifiers comprising the electron discharge valvesI20 and I2I the inductances iii! of each stage are adapted to beparalleled by respective suitable capacitors designated for each stageby the reference numerals I35a, I35b, I35c, I05d, I05e, I351, I000,I35h, I351, I357 and I35k. All of these capacitors for each stage have acommon terminal which is connected to one terminal of the associatedinductance I32. The other terminals of the capacitors I35a to I35kinclusive are connected to a plurality of contacts arranged in equallyspaced relationship about a portion of the 16 circumference of a circle.These contacts are designated by the reference numerals 0o, Ib, I40c,I40d. I402, I401, I409, I40h, 0!, I401, and 01:, which together with thecontacts I40m. I401: and I401: are arranged in equally spacedrelationship in the form of a semicircle as is clearly indicated in Fig.lb of the drawings. A rotary switch arm III is adapted to successivelyengage the contacts I40a to 0;: inclusive in that order during a halfcycle of rotation. The values of the capacitors I054 to I801 are chosenso as to provide with the associated inductance I02 a plurality of tunedcircuits, each corresponding to a different one of the audio frequenciesproduced by virtue of the resistances 44a to 441 and a to 451respectively, and the step-tuned audio frequency amplifier unitscomprising the discharge valves I20 and I2I will successively pass audiofrequency signals capable of being produced by the audio oscillators 23as the appropriate capacitors I38 are rendered effective by the rotaryswitch arms I4I. In'other words, during each cycle of rotation, whichpreferably is once per minute all of the frequencies capable of beingproduced by the audio oscillators 23 are capable of being passed by thestep tuned audio frequency amplifier unit in at the instant that theappropriate contacts are engaged by the rotating switch arms "I. Theswitch arms I of each of the step-tuned amplifier stages areinterconnected by a suitable shaft designated by the reference numeralI43 which is drivingly connected to a syncnronous motor unit I44preferably capable of driving the switch arms I4I at one revolution perminute. The capacitors I35]: and associated contacts I401: are providedto permit tuning of the step-tuned amplifier unit in to the frequencyproduced by the audio oscillators 23 when the associated receivers aretuned to all other stations.

It will be apparent that unless one or more of the wave signal receiversII) are turned on there is no necessity for the step-tuned amplifiersdescribed above to be eifective. Accordingly the synchronous motor I44is normally deenergized and is only energized when one or more of thewave signal receivers I0 are turned on. Accordingly the contacts 40,II4b and II4c of the associated relays I I20. H21) and Il2c areconnected in parallel with each other and the parallel arranged contactsare connected in series with the power supply from the house wiringcircuit 25 to the synchronous motor unit I44. When any one of the relaysII2a, I I2!) or I I2c is deenergized indicating the receipt of a carriersignal by one or more of the fixed tuned receivers 96, the synchronousmotor unit I44 is energized. The synchronous motor unit I44 furthermoredrives through the shaft I43 a rotary switch arm I46 substantiallyidentical with the rotary switch arms I4I capable of successivelyengaging a plurality of spaced contacts Illa, I4lb, I4lc, I4ld, I4Ie,I4lj, I410, I4Ih, I411, I417, um, I4'Im, Min, and Hip in an identicalmanner with the contacts I40 marked with corresponding subscripts. Thesecontacts correspond exactly to the contacts I40 and are arranged alongthe circumference of a half circle so as to be successively engagedduring one half cycle rotation of the switch arm I48. The contacts I40m,I401: and I401) have no function and are not connected to anything asindicated in the drawings but correspond to the contacts I4lm, I411: andI41 which contacts form a part of the apparatus for designating 17whether one or more of the wave signal receivers I6 are turned on.

The amplified audio frequency at the output of the two-stage step-tunedaudio frequency amplifler is coupled by means of a coupling capacitor 8to the diode section of an electron discharge valve in the form of adiode-triode I56 so as to rectify any audio frequency appearing at theoutput of the step-tuned audio frequency amplifiers. The cathode of thediode triode electron discharge valve is grounded through a suitableresistor iii, and the control electrode of the triode section isconnected to the cathode so as to be supplied with a positive bias whena suitable signal is detected by the diode section thereof. The triodesection consequently acts as a direct current amplifier and the platecircuit is connected to a source of direct current +B potentialdesignated by the reference numeral I03 through the winding I54 of arelay I55 having normally open contacts I66. Whenever an audio frequencysignal is detected by the diode section of the valve I60, suiilcientcurrent flows through the winding I56 of the relay I55 so as to closethe contacts I56. The contacts I66 are adapted to connect the contactsI410 to 1k inclusive to ground.

Any suitable recorder may be provided to record the tuning conditions ofthe wave signal receivers Illa, I01) and Illc. As illustrated, therecorder 96 comprises a movable recording or record receiving elementI6Il, which is illustrated as a tape having sprocket holes adjacent theedges thereof adapted to be engaged by a suitable sprocket I6I which isdriven by a synchronous motor I62 continuously connected to a suitablesource of potential. The synchronous motor I62 is connected to thesprocket I6I by means of the shaft I63. Preferably the synchronous motorI62 is energized from the house wiring circuit 25 at all timesregardless of whether or not other parts of the apparatus at the centralstation 95 are energized, thereby insuring continuous movement or atleast movement in a predetermined manner with respect to time of therecord receiving ele ment I60. The recorder 96 also includes the tapesuppl spool I65 and the take up spool I66 together with suitable meansfor maintaining the tape in a taut condition.

The means for producing a record or trace on the recording element I66is illustrated as comprising a stylus I61 which is supported for arcuatemovement on a pivot I66 so that the inscribing portion I61a is adaptedto move transversely of the tape or record receiving element I66. Thestylus I61 is connected by means of a suitable link I69 and a crank I10with the shaft I43 of the synchronous motor unit I. It will be apparentthat with this arrangement the position transversely of the recordreceiving element I66 of the inscribing portion I 610 of the stylus I61will correspond to the position of the switch arms Ill and I46 withreference to their particular contacts Illl and I41. As far as thecontacts Ila to llllk are concerned the position of the stylus I61 willcorrespond to a particular frequency produced by the audio frequencyoscillators 26 described above and consequenty to a particular tuningcondition of one or more of the wave signal receivers Illa, IIlb andIllc.

The inscribing portion I611: is normally not in contact with the recordreceiving element I66. In order to produce a trace the stylus pivotpoint I66 is supported on a movable carriage I13 mounted for limitedmovement about a pivot I12.

such a manner that the inscribing portion IBM is not in trace producingengagement with the recording element Hill. A portion of the carriageI13 forms the armature of an electromagnet comprising a winding I16. Oneterminal of the winding I16 is connected to the source I63 of +3potential while the other terminal is connected by the conductor I11with the switch arm I46. With this arrangement it will be apparent thatwhenever the contacts I56 are closed and the switch arm I46 is in aposition to contact one of the contacts 1a to 1k inclusive theinscribing portion I610 may be caused to engage in a trace producingmanner the movable record receiving element I60. It will be apparentthat with this arrangement the record receiving element I60 will bechannelized into equally spaced channels as indicated by the fineparallel lines numbered I to II corresponding to the ten stations towhich the wave signal receivers Illa, Ill) and Illc are likely to betuned. The 11th channel marked A0 in Fig. lb of the drawings isrepresentative of the all other stations channel.

In order to produce an indication of which wave signal receivers areturned on. a plurality of three additional channels are provideddesignated as Illa. Iflb and Illc respectively which correspond to thecontacts 1m, 1n and I41p. The contact 1m is connected to ground throughthe contacts II3c of the relay II2c. Similarly the contact 111. isconnected to ground through the contacts I lib of the relay 2b, and alsothe contact 1 is connected to ground through the contacts I lid of therelay I Ila. Whenever one or more of the relays Ilia, "2b or Illc areenergized one or more of the contacts I41m, 1n, and 141p are grounded toindicate that one or more 0 the wave signal receivers Ina, Illb or IIlcare turned on. When the stylus I61 is in the position corresponding tothe channels IIIa. I61) or Illc a trace will be produced depending uponwhether or not. the associated contacts engageable by the switch arm '6are grounded through the contacts I I3 or one or more oi the relays III.It will be noted that since the contacts I46 and I61 are arranged in asemicircle the stylus I61 can produce a trace while moving in only onedirection across the recording element I66 and for the reverse directionof movement no trace will be produced since the switch arms III and I46engage no contacts for this half cycle of rotation.

With this arrangement it is apparent that readily decodable informationis obtained. Since the indications of the tuning conditions of thereceivers appear. on the record receiving element I66 in equally spacedchannels, the decoding process is greatly simplified. Only whenreceivers are simultaneously turned on or turned oiI will there be anyambiguity as to the interpretation of the record and the rare occurrenceof this insures obtaining a readily decodable record at substantiallyall times.

In view of the detailed description which has been included above theoperation of the above described apparatus will be apparent to thoseskilled in the art. A signal will be produced at each receiverindicative of the tuning condition of the receiver which is transmittedas the modulation component of a suitable carrier. The choice of thecarrier frequency immediately acts as a means to identify the particularreceiver involved and the audio frequency modulation components areindicative of the station to which the receiver is tuned. By means of asimple apparatus in the A suitable spring I14 biases the carriage I13 in76 form of a step tuned audio frequency amplifier and translating unit aclear and unambiguous record of the tuning condition of one or more wavesignal receivers is readily produced with the information contained inequally spaced channels on the recording element. Furthermore, byemploying the adiustably variable width contacts of the presentinvention accurate indications are obtained regardless oi the particularposition or the tuning shaft of the receiver. It will be apparent that amuch larger number oi channels than the number illustrated by way 01'example may be employed which may be indicative of one or more ofamplitude modulation. frequency moduiation and television signals.Furthermore a recording element in the term of a magnetic tape or othersuitable means might equally well be employed.

It will be apparent to those skilled in the art that the presentinvention is not limited to the particular constructions andarrangements shown and described but that charges and modifications maybe made without departing from the spirit and scope of the invention.and it is aimed in the appended claims to cover all such changes andmodifications.

What is desired to be secured by Letters Patent or the United States is:

1. In a system for providing an indication of the tuning condition oi awave signal receiver of the type provided with a movable tuning elementfor conditioning said receiver for signal reception from diiferenttransmitting stations operating at diflerent carrier frequencies andwherein said receiver is capable of receiving signals from one of saidtransmitting stations over a greater increment of movement of saidtuning element than others of said transmitting stations whereby saidstations appear to have diilerent band widths with resepect to movementof said tuning element, a position switch comprising a common contactmember-and a plurality of contact means respectively corresponding todlflerent transmitting statiom likely to be tuned in by said receiver,driving meam actuated by said tuning element for relatively moving saidcontact member and said contact means to produce engagement of saidcontact member with a predetermined one of said conbct meanscorresponding to the predetermined one of said transmitting stations towhich said receiver is tuned for signal reception, and mean for theengagement of said one of said contact means by said contact member forall pcsitlom of said element at which signals from said one transmittingstation are received by said receiver.

2. In a system for providing an indication of the tuning condition oi. awave signal receiver of the type provided with a movable tuning elementfor conditioning said receiver for signal reception from diflerentstations operating at different carrier irequencies and wherein saidreceiver is capable oi receiving signals from one of said transmittingstatiom over a greater increment of movement oi said timing element thanothers of said transmitting stations whereby said stations appear tohave diil'erent band widths with respect to of said tuning element, aposition switch comprising a common movable contact member and aplurality of contact means respectively co to the diilerenttransmittingstationsliknlytobetlmedinbysaidreceiver, driving meansactuated by said tuning element connected to said contact member forcausing said contact member to engage the predetermined one of saidtransmitting stations when said predetermined one of said transmittingstations is tuned in by said receiver, and means for insuring theengagement of said one of said contact means by said contact member forall positions oi said element at which signals from said onetransmitting station are received by said receiver.

3. In a system for providing indications of the transmitting stations towhich a tunable wave signal receiver is tuned for signal reception, saidreceiver being provided with a movable tuning element for conditioningsaid receiver for signal reception from different transmitting stationsoperating at different carrier frequencies and being capable ofreceiving signals from at least one oi said transmitting stations overan increment of movement of said tuning element which is greater thanthose increments of movement of said tuning element over which others ofsaid transmitting stations may be received by said receiver, a positionswitch comprising a common contact member and a plurality of contactmeans respectively corresponding to diiferent transmitting stations fromwhich signals may be received by said receiver. driving means operatedin response to operation of said tuning element for relatively movingsaid contact member and said contact means to produce engagement 0! saidcontact member with the predetermined one 01' said contact meanscorresponding to the transmitting station to which said receiver istuned for signal reception. means for insuring engagement between saidone of said contact means and said contact member throughout allpositions 01' said tuning element at which signals from said onetransmitting station are received by said receiver, and meansselectively controlled by said position switch for producing indicationsof the transmitting stations to which said receiver is tuned for signalreception.

4. In a system for providing indications oi the transmitting stations towhich a tunable wave signal receiver is tuned for signal reception, saidreceiver being provided with a movable tuning element for conditioningsaid receiver for signal reception from diii'erent transmitting stationsoperating at difierent carrier frequencies and being capable ofreceiving signals from at least one of said transmitting stations overan increment of movement of said tuning element which is greater thanthose increments of movement of said tuning element over which others ofsaid transmitting stations may be received by said receiver, a positionswitch comprising a movable contact member and a plurality of contactmeans respectively corresponding to the diiterent transmitting stationsfrom which signals may be received by said receiver. driving meansoperated in response to operation of said tuning element ior moving saidcontact member to produce engagement oi said contact member with thepredetermined one of said contact means corresponding to thetransmitting station to which said receiver is tuned for signalreception, means comprising a predetermined effective width oi said onecontact means corresponding to the possible limits of movement of saidtuning element at which smnals from said corresponding transmittingstation are receivable for insuring engagement between said one of saidcontact means and said contact member throughout all positions of saidtuning element at which signals from said one transmitting station arereceived by said receiver. and means selectively controlled by saidposition switch for producing indications of the transmit- 21 tingstations to which said receiver is tuned for signal reception.

5. In a device for providing at a remote point an indication of thetuning condition of a wave signal receiver, means for developing asignal having a plurality of distinct characteristics comprising apluralit of variably positioned contacts, means for selectivelyrendering effective one of said contacts at a time for developing acorresponding signal having a distinct characteristic, and means forinterconnecting said last mentioned means and said wave signal receiverto cause different ones of said contacts to be rendered effective inresponse to tuning of said receiver to different signal channels, saidcontacts effectively differing in physical characteristics in accordancewith the apparent band widths of the associated channels as viewed atsaid receiver so that tuning said receiver to any position in anycnannel for which contacts are provided regardless of the apparent bandwidth of said channel as viewed at said receiver will cause a signalhaving the associated distinct characteristic to be produced.

6. In a system for providing at a remote point an indication of thetuning condition of a wave signal receiver having a tuning shaft, thecombination of means for developing a signal having a plurality ofdifferent characteristics including a plurality of contacts, movablemeans adapted selectively to render said contacts effective, means forinterconnecting said movable means with the tuning shaft of said wavesignal receiver to cause different ones of said contacts to be renderedeffective and different characteristics to be produced in response totuning of said receiver to different signal channels, the particularcharacteristic produced at any time being dependent on the channel towhich said receiver is tuned, said contacts differing in effectivephysical size in accordance with the apparent band width of theassociated channel as viewed at said receiver so that tuning saidreceiver to any position in any channel for which contacts are providedregardless of the band width of said channel will cause a signal havingthe particular associated characteristic to be produced.

HENRY A. RAHMEL.

No references cited.

